JPS649059B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] "Field of Industrial Application" The present invention relates to a fluid energy pulverizer (hereinafter referred to as a jet mill).

"Prior Art" The demand for finer powders has become stronger and stronger in recent years, and the particle size range of fine powders is also required to be narrower. A large number of pulverizers and classifiers for obtaining carefully selected fine powder have appeared to meet this demand. Among these, the application technology of fine ceramics, which represents modern science, is remarkable.
Jet mills are the mainstream pulverizers used in the process of supplying these raw material powders. The crushing mechanism in the jet mill also includes a rotating type, a collision type, or a combination type of collision and rotation, and the crusher body is equipped with a classification mechanism having a classification chamber different from the crushing chamber. There is something.

This classification mechanism utilizes the property that coarse particles gather on the outside of the flow and fine particles gather on the inside of the flow in a curved flow such as the swirling movement of crushed material after a crusher, and a partition wall is formed in the classification chamber. The inlet end of the classifying member is arranged to face the flow, and the ratio of coarse particles to fine particles is divided depending on the position of the inlet end of the classifying member.

A system in which this classification member is placed immediately after the center of the rotating crushing chamber is shown in Japanese Patent Publication No. 47-27284, and a system in which the classifying member is placed in a classification chamber adjacent to the rotating crushing chamber. is a special public official in 1978.
There is one shown in Publication No. 27177.

“Problems to be Solved by the Invention” All of these classification mechanisms mainly perform swirling inertia classification using the residual pressure of jet air used for crushing, or classification based on the Coander phenomenon, and the classification effect is not unique to the classification mechanism. It depends only on the speed at which the That is, it is determined by the amount of jet air. Furthermore, as a result of the action being performed at a location where the inertial force necessary for solid classification is weakened, not only does the particle size have a large classification point, but the fine powder that becomes the product also has a particle size composition with a wide range.

However, recently there has been a strong demand for uniformity in particle size for products. However, conventional classification mechanisms have a fixed structure, and the classification member is either a single unit approximately the size of the entire machine frame, or is integrated with another frame member. Therefore, if the classification ratio of coarse particles to fine particles is to be changed by changing the position of the inlet of the classification member, it is necessary to change the entire classification member. On the other hand, there is a problem in that when the inlet part of the classification member is rubbed and worn by the crushed material, the inlet part changes its position and the classification state changes.

An object of the present invention is to eliminate the above-mentioned drawbacks of the classification device provided in a fluid energy type pulverizer and to provide a fluid energy type pulverizer that can always stably produce only fine powder.

[Structure of the invention]

"Means for solving the problem" The present invention arranges a nozzle, a solid-gas mixing chamber, and an accelerator tube in a straight line so that solid gas is mixed and collides with a collision plate, and the outlet side of the accelerator tube is opened at a position. This classification system is equipped with a rotating grinding chamber surrounded by a nozzle that blows air into the interior, a fine powder chamber surrounding an accelerator tube, and a fine powder chamber with an annular classification plate outside the fine powder chamber. The present invention is a pulverizer that is provided with a rectifying zone that passes through the rotating pulverization chamber and the classification chamber, and the inlet of the classification plate is a removable annular classification chip.

``Operation'' By replacing only the classification tip, the position of the entrance of the classification member can be changed, so products with the required particle size and particle size distribution can be obtained, and even if the classification plate is worn out, it can be dealt with simply by replacing the classification tip.

"Example" Hereinafter, an example of the present invention will be described with reference to the drawings.
FIG. 1 is a longitudinal sectional view. A head body 2 is removably fixed to the body 1, and a crushed material supply head 4 equipped with a hopper 3 for supplying crushed materials (raw material to be crushed is called crushed material) is fixed to the head body 2.
The body 1 is formed in the shape of a hollow rotating body in the cross section shown, and a nozzle 5 is fixed to the powder feed head 4 adjacent to the hopper 3 on its center line, and the outlet of the nozzle 5 and the hopper 3 are connected to each other. The outlet end opens into a solid-air mixing chamber 7 provided in the upper part of an accelerating tube 6 fitted and fixed in the center of the head body 2 on the same center line as the nozzle 5, and constitutes an ejector.

A classification chamber 8 is provided around the acceleration tube 6 on the head main body 2 side between it and the body 1, and a rectification zone 9 is provided following the classification chamber 8. In the classification chamber 8, a part of the conical classification chamber is used as a classification member that divides the conical classification chamber into a small conical fine powder chamber 11 into which products with smaller particle size are introduced and an annular fine powder chamber 12 which introduces crushed powder with larger particle size. An annular classification plate 13 is integrally provided with the head body 2, and the classification plate 13 has an annular classification tip 14 concentric with the body 1 at the small diameter end of the inlet portion. That is, as will be described later in the explanation of the action, the classification plate 1
3 is concentric with the swirling flow around the acceleration tube 6. This classification chip 14 is provided with a male thread that fits into a female thread provided at the inner diameter end of the classification plate 13, and is designed to be detachable. Its shape is such that the inner diameter side has a sharp cutting edge with an acute angle pointing diagonally downward toward the center in FIG. The classification plate 13 is made of a wear-resistant material such as super steel alloy steel.

The fine powder chamber 11 communicates with a collector (not shown) through two discharge passages 15 provided in the head body 2. The fine powder chamber 12 communicates with the solid-gas mixing chamber 7 through a plurality of circulation paths 16 provided radially in the head body 2, and a powder chamber 12 is screwed in the radial direction of the head body 2 in the middle of the circulation path 16 and is movable back and forth. A flow rate regulating valve 18 including a needle valve 17 is configured.

As described above, the classification plate 13 equipped with the classification chip 14 is arranged in the classification chamber 8 surrounded by the body 1 and penetrated by the accelerator tube 6 concentric with the body 1, and coarsely crushed particles, i.e. A classification device is constituted by a fine powder chamber 12 that communicates with a circulation path for collecting crushed powder, and a fine powder chamber 11 that communicates with a discharge path that collects finer crushed powder.

On the opposite side of the body 1 to which the head body 2 is attached, an annular side wall 21 is fitted into an upper wall 19 integral with the body 1, an annular air reservoir 22 is fitted into the outside of the side wall 21, and an annular air reservoir 22 is fitted into the upper wall. The bottom wall 23 is fitted into the side wall 21 from the side opposite to the side wall 19, and the bottom wall 23, the side wall 21, and the air reservoir 22 are fastened together to the top wall 19 (the fixing method is not shown). A ratcheted end of the accelerator tube 6 protrudes into a rotating crushing chamber 24 formed by being surrounded by a top wall 19, a side wall 21, and a bottom wall 23.
The end of the acceleration tube 6 faces a collision plate 25, which is a fixed wall fixed to the bottom wall 23, with an appropriate distance therebetween.
A material having high hardness corresponding to the crushed material is conveyed to the collision plate 25. For example, if the crushed material is alumina, which is a ceramic material, the collision plate 25 is made of ceramic.

As shown in FIG. 3 of the BB cross-sectional view of FIG. A plurality of rotating crushing nozzles 26 penetrate into the rotating crushing chamber 24 from inside the air reservoir 22.

From the compressed air source 27, compressed air pipes 28, 29 communicate with the nozzle 5 and the air reservoir 22.

In the operating state, compressed air is supplied from the compressed air source 27 to the nozzle 5 through the compressed air pipe 28, and at the same time, air is supplied from the compressed air pipe 29 to the rotating crushing nozzle 26 via the air reservoir 22. The compressed air blown from the nozzle 5 is ejected from the nozzle end as a jet flow, and in the solid-gas mixing chamber 7, the hopper 3 is heated by the vacuum pressure generated around the jet flow.
The crushed material inputted from the pulverized material is sucked in, and a part of the crushed material is also sucked in through the circulation path 16, as will be described later. These are caught up in the jet flow in the solid-gas mixing chamber 7, and the solid-gas mixed jet flow continues into the solid-gas mixing chamber 7 through an accelerating tube 6 which serves as a divergent nozzle, where the pressure is converted into velocity energy and the pressure is increased. The crushed material is ejected at high speed and violently collides with the collision plate 25, and the crushed material is finely pulverized and scattered radially into the rotating crushing chamber 24.

The compressed air that has entered the air reservoir 22 blows a jet flow into the rotating crushing chamber 24 through the rotating crushing nozzle 26, and a single swirling flow is generated in the rotating crushing chamber 24 around the accelerating tube 6. The crushed powder in the rotating crushing chamber 24 is directly accelerated by the jet flow of the rotating crushing nozzle 26, and the crushed powder collides with other crushed powder, and the crushed powder due to the collision with the collision plate 25 is further crushed. A characteristic of rotary crushing is that it has a strong effect of rounding the corners of the crushed material, that is, it has a strong grinding effect.
Centrifugal force acts on the crushed powder due to high-speed rotation in the rotating crushing chamber 24, and large particles are further crushed by the rotating crushing nozzle 26 while rotating on the side wall 21 side, becoming finer. . The crushed powder that has become fine due to the rotating collision action loses its centrifugal force,
The air flows through the rectification zone 9 while being accompanied by the flow of air, which is a combination of the air that has passed through the nozzle 5 and the acceleration pipe 6 and entered the rotating crushing chamber 24, and the air that has entered the rotating crushing chamber 24 from the rotating crushing nozzle 26. move on. Each particle of the fine powder and pulverized crushed powder through the collision crushing process and the rotation crushing process is subjected to centrifugal force in the rectification zone 9, and the fine powder with a large mass is centrifugally classified to the outside and the fine powder with a small mass is centrifugally classified to the inside. The powder flows into the classification chamber 8 and is classified into fine powder and fine powder by the classification plate 13 equipped with a classification chip 14.The fine powder enters the solid-gas mixing chamber 7 through the circulation path 16, and is mixed with the crushed material supplied from the hopper 3. A collision pulverization step in which the mixture is mixed, accelerated in the acceleration tube 6, ejected and pulverized by collision against the collision plate 25; a step in which the pulverized materials are collided and pulverized in the swirling pulverization chamber 24; The process of rectifying the liquid and returning to the classification chamber 8 is repeated, thereby gradually pulverizing the liquid. The fine powder is collected in the fine powder chamber 11 and taken out from the discharge passage 15 by a collector (not shown).

Now, let us consider the behavior of particles at the inner diameter portion of the classification chip 14 in the classification chamber 8. FIG. 4 is a plan view of the classification room. The flow state of the fluid inside the classification chamber 8 is centered around the circumferential direction velocity U _t of the crushed powder particles M.
A quasi-free vortex close to a free vortex is formed which is inversely proportional to the radius r of the twist. Furthermore, from near the inner diameter of the classification chip 14 to the inside, an inward radial flow (velocity
U _r and a stronger upward axial flow than outside.

If the centrifugal force exerted by the swirling speed is greater than the force exerted by the inward flow, particles in the vicinity of the internal diameter r _p of the classification tip 14 will move from the outer fine powder chamber 12 to the circulation path 16 through a small The powder flows from the inner fine powder chamber 11 to the discharge path 15 side.
The critical particle diameter d _p to be classified at this time is d _p = (18 μ r _p U _r /ρ _p U _t ² ) ^1/2 , where μ: viscosity of air, ρ _p : density of powder to be classified. I can express it.

On the other hand, u _t・r ⁿ = const. However, from the equation of the velocity distribution of the quasi-free vortex shown by the equation 0<n<1, the critical particle diameter, which is the particle classification diameter, changes the inner diameter r _p of the classification chip 14. This allows for movement operations.

Therefore, the head main body 2 is removed from the body 1, the accelerator tube 6 whose lapped end diameter is larger than the inner diameter of the classification chip 14 is unscrewed and removed, and the classification chip 14 is removed.
By exchanging the particles, the particle size and particle size distribution of the powder particles to be manufactured can be adjusted to a desired size.

When the flow rate adjustment valve 18 narrows the width S of the annular valve opening to reduce the flow rate of the circulation path 16, the fine powder chamber 12
The air pressure of
The amount of crushed fine powder that enters and recirculates is reduced, and the average number of times the crushed powder is repeatedly crushed is reduced, so that the particle size of the crushed powder in the classification chamber 8 becomes larger on average. On the other hand, the eddy current on the fine powder chamber 12 side in the classification chamber 8 is suppressed, and the axial flow toward the fine powder chamber 11 becomes stronger, so that larger particles of crushed powder flow into the fine powder chamber 11 and are taken out from the discharge path 15. The average particle size becomes larger and the particle size distribution becomes more dispersed.

In this way, the basic classification limit is changed in the classification chip 14, and the flow rate adjustment valve 18 has the function of adjusting the classification limit determined by one classification chip 14.

FIG. 5 is a longitudinal sectional view of another embodiment of the flow rate regulating valve 18. Radial circulation path 16 of head body 2
A rotary valve 31 is slidably fitted into a hole coaxial with the direction.
The rotary valve 31 has a tubular shape and has a plurality of valve ports 32 having different diameters in the radial direction, and any one of the valve ports 32 connects the fine powder chamber 12 and the circulation path 16, so that the powder flows through the circulation path 16. This is to adjust the amount of fine powder. The rotary valve 31 is fixed by a set screw 34 screwed into the head body 2 via a washer 33, and a stopper 35 screwed into the internal thread is opened in the head body 2 toward the outer periphery of the rotary valve 31.
The set screw 34 is loosened, and a needle-like member is used to rotate the rotary valve 31 through the hole for the stopper 35 to select the other valve port 32 to communicate with the fine powder chamber 12.

In the embodiment, the classification plate is integrated with the head body, and the classification chip is screwed into the female thread provided at the end of the classification plate, so that when classifying fine powder of a desired particle size or less, the classification chip can be replaced by simply turning it.

The embodiment is equipped with a classification chip and a collision crusher,
Swirling crushing and entering the classification chamber through the gyrating zone;
Since a flow rate regulating valve is provided in the circulation path for recirculating the relatively coarse particles classified in the classification chamber, the particle size and particle size distribution of the crushed powder can be adjusted without disassembling the device.

In this embodiment, a composite fluid energy type micro-pulverizer is used as a fluid energy type crushing means, which uses a means for colliding the crushed material accompanying a jet flow against a fixed wall (impingement crushing means) and a crushing means for causing a swirling collision (swivel crushing means). Although the explanation has been made using a crusher, it goes without saying that the present invention is also effective in a crusher equipped with either a collision crushing means or a rotating collision means.

〔Effect of the invention〕

In the present invention, a nozzle, a solid-air mixing chamber, and an accelerator tube are arranged in a straight line so that solid air is mixed and collided with a collision plate, and a nozzle is provided at a position where the outlet side of the accelerator tube opens to blow air into the interior. A rotating crushing chamber is arranged around the accelerating tube, a classifying chamber is provided with a fine powder chamber with an annular classification plate placed between the fine powder chamber surrounding the accelerating tube, and the rotating crushing chamber and the classifying chamber are arranged. In a pulverizer equipped with a rectification zone to pass through, the inlet of the classification plate is a removable annular classification chip, so the limit particle size can be changed by simply replacing the classification chip. This not only makes it easy to obtain the product particle size that requires fine adjustment, but also eliminates the need for a stand-alone classifier as part of the pulverization system, resulting in lower equipment costs and the need to replace worn-out classifying members by simply replacing parts. Therefore, it greatly contributes to reducing production costs, including operational management, and stabilizing products.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line A-A in FIG. 1, and FIG. 3 is a cross-sectional view taken along line B-B in FIG.
4 is a sectional view taken along the line CC in FIG. 1, and FIG. 5 is a longitudinal sectional view of another embodiment of the flow rate regulating valve. DESCRIPTION OF SYMBOLS 1...Body, 2...Head main body, 3...Hopper, 4...Crush feed head, 5...Nozzle, 6...
...Acceleration tube, 7...Solid gas mixing chamber, 8...Classification chamber, 9
... Rectification zone, 11 ... Fine powder chamber, 12 ... Fine powder chamber, 13 ... Classifying plate, 14 ... Classifying chip, 15
...Discharge path, 16...Circulation path, 17...Needle valve, 18...Flow rate adjustment valve, 19...Top wall, 21...
...Side wall, 22...Air reservoir, 23...Bottom wall, 24...
... Rotating crushing chamber, 25... Collision plate, 26... Rotating crushing nozzle, 27... Compressed air source, 28, 29...
...Compressed air pipe, 31...Rotary valve, 32...Valve port,
33... washer, 34... set screw, 35... plug.

Claims (1)

[Claims] 1 Arrange the nozzle, solid-gas mixing chamber, and acceleration tube in a straight line so that the solid gas mixes and collides with the collision plate, and surround the nozzle that blows air toward the inside at the position where the exit side of the acceleration tube opens. A rotating crushing chamber with a rotating crushing chamber is provided, and a rotating crushing chamber surrounding the accelerating tube and a classifying chamber equipped with a fine powder chamber are passed through the rotating crushing chamber and the classifying chamber with an annular classification plate placed between them on the outside of the fine powder chamber. A pulverizer provided with a rectification zone, wherein the inlet portion of the classification plate is a removable annular classification chip.